Portland’s spring is about to flip from mild to summerlike. Forecast models show a much warmer air mass settling over the region Saturday and Sunday, sending temperatures from just below 80 on Saturday to well into the 80s on Sunday and Monday.
That surge would come after a spring that has already ranked as Portland’s ninth warmest in records going back about 85 years. The season has brought its share of cool, gray days mixed with sunny, warm stretches, including Easter Sunday, but the broader pattern has leaned warm enough to push the city into the top 5-15 warmest springs so far.
The heat matters now because the ground conditions are already fragile. Most areas in the northern Oregon Cascades below 4,500 feet are snow-free, while 49 inches of snow still remains at 5,400 feet on Mt. Hood. Across Oregon, almost three-quarters of the state is in some form of drought, and the disappearing snowpack is feeding that spread.
Rain has been close to average for much of the region, but it has not been enough to offset the warmer winter that left the snowpack in poor shape. The result is a landscape that is drying out quickly just as the calendar turns toward May, with the usual mountain runoff season already starting from a weaker base than normal.
The next stretch looks even drier and warmer. Forecast guidance points to 7 to 10 days of warmer and drier than normal weather, with a light easterly wind and 850mb temperatures around or a little above +15 C driving a notable spike in daytime highs. The warmup is expected to continue into the first week of May, and the Euro AI Forecast System shows the relatively warm and dry pattern holding into week 2 as well. The GFS precipitation anomaly forecast for the next 15 days is much drier than normal, underscoring how little relief the region is likely to get soon.
By this weekend, even potted plants outside are going to need watering. With temperatures expected to run 20-25 degrees above normal in places and record highs generally around 90 in early May, Portland weather is heading into a brief but sharp dry spell that will deepen the strain on a region already short on snow and water.